Means for controlling and regulating the braking of vehicles

ABSTRACT

The invention relates to a system for controlling and regulating the braking of a vehicle, comprising a braking circuit common to a plurality of wheels (or sets of wheels) of the vehicle, measuring means associated with each wheel (or set of wheels) for continuously producing individual signals which are direct functions of the decelerations of said wheels (or sets of wheels) respectively, anti-locking means responsive to the last mentioned signals respectively adapted to release locally the braking exerted on those of the wheels the decelerations of which exceed a predetermined threshold, a summing unit supplied with said individual signals delivering a working signal representative of the sum of said individual signals and a comparator of the working signal and of a signal which is representarive of a preset reference deceleration for the vehicle, adapted to slave the increase or decrease in braking power applied to the vehicle through the braking circuit to the difference between the two last mentioned signals, whereby the overcoming of the locking of a wheel is compensated by an increased braking action on the other wheels and therefore does not affect the execution of a preset deceleration program for the vehicle.

United States Patent 1 3,682,512 Malon et a1. [45] Aug. 8, 1972 [54]MEANS FOR CONTROLLING AND 3,520,575 7/ 1970 Steigerwald ..303/21 CGREGULATING THE BRAKING OF 3,537,758 11/1970 Buhler et al. ..303/21 BEVEHICLES [72] Inventors: Jean Pierre Malon, Maisons Alfort; Joseph W.Adde, Montfermeil, both of France [73] Assignees: Compagnie des Freinset Signaux Westinghouse, Freinville-Sevran; Societe Inter-Elec,Aubervilliers, France [22] Filed: Nov. 7, 1969 [21] Appl. No.: 874,778

[30] Foreign Application Priority Data Nov. 13, 1968 France ..68173427[52] US. Cl. ..303/20, 188/181 A, 303/21 P [51] Int. Cl. ..B60t 8/08,B60t 13/68 [58] Field of Search ..188/181; 303/20, 3,21;

[56] References Cited UNITED STATES PATENTS 3,158,409 11/1964 Hughson eta1 ..303/15 3,374,035 3/1968 Howard ..303/20 3,384,033 5/1968 Ruff..105/61 3,398,995 8/1968 Martin ..303/21 A X 3,402,972 9/1968 Cooper etal. ..303/20 3,494,671 2/1970 Slavin et a1 ..303/21 A X 3,499,689 3/1970Carp et al. ..303/21 A X 3,545,817 12/1970 Yarber ..303/21 P PrimaryExaminer-Duane A. Reger Assistant Examiner-Stephen G. KuninAtt0rneyMcClure & Weiser [5 7] ABSTRACT The invention relates to asystem for controlling and regulating the braking of a vehicle,comprising a braking circuit common to a plurality of wheels (or sets ofwheels) of the vehicle, measuring means associated with each wheel (orset of wheels) for continuously producing individual signals which aredirect functions of the decelerations of said wheels (or sets of wheels)respectively, anti-locking means responsive to the last mentionedsignals respectively adapted to release 10- cally the braking exerted onthose of the wheels the decelerations of which exceed a predeterminedthreshold, a summing unit supplied with said individual signalsdelivering a working signal representative of the sum of said individualsignals and a comparator of the working signal and of a signal which isrepresentative of a preset reference deceleration for the vehicle,adapted to slave the increase or decrease in braking power applied tothe vehicle through the braking circuit to the difi'erence between thetwo last mentioned signals, whereby the overcoming of the locking of awheel is compensated by an increased braking action on the other wheelsand therefore does not affect the execution of a preset decelerationprogram for the vehicle.

10 Claims, 1 Drawing Figure ELEMENT THQESII fLFMENY F R EQ. 56/1501?S/IAPER MULI couvenraR I l I L v a L 151L 91; ZQ Z l l iii idi MEANS FORCONTROLLING AND REGULATING THE BRAKING OF VEHICLES This inventionrelates to means for controlling and regulating the braking of avehicle, of the kind wherein the vehicles braking system is slaved tothe difference between a slowing down or braking command signalrepresentative of a selected reference deceleration value and a signalcontinuously representative of the measured actual deceleration of thevehicle, in such manner as to cause, responsively to such slowing downcommands, cancellation of said difference to within the precisioncapability of said control and regulating means. The invention relatesmore particularly though not exclusively to such control and regulatingmeans as are designed for application to trains and motor vehicles.

In preferred embodiments of these control and regulating means, recourseis had, for the purpose of continuously measuring the actualdeceleration of the vehicle (at least while said slowing down or brakingcommand is applied), to means for measuring the angular velocity of awheel axle which deliver a signal to a differentiating element whichprovides, at its output a signal which is at all times representative ofsaid actual deceleration.

However, it is common knowledge that it is necessary, especially whererailway vehicles are concerned, to equip the latter with meansassociated with each wheel or set of wheels which, during braking orslowing down of the vehicle, are adapted to prevent slipping or lockingof these wheels on their associated tracks, particularly under theeffect of accidental loss of adhesion. in a preferred embodiment of suchmeans, the latter are capable, responsive to the sudden angulardeceleration experienced by a wheel tending to become locked, ofoverriding, or at any rate releasing sufficiently, the braking forceapplied to the associated wheel or set of wheels in order to eliminateany risk of locking.

in addition to the fact that the wheel locking effect which in itselfhas serious disadvantages in that it notably causes defects in wheelroundness is liable to disrupt the actual-deceleration measurementrequired for the vehicle deceleration regulating function referred to,compensating for such locking tendency by releasing the brake also runscounter to proper implementation of the slowing down program imposed onthe vehicle by said control and regulating means. It is accordingly theobject of the present invention to provide improved control andregulating means of the kind referred to, and means for preventingaccidental wheel locking, that are capable of engendering a brakingeffect to suit a predetermined deceleration program and of affordingcomplete protection against wheel locking.

The present invention consists, principally in a vehicle equipped with abraking circuit common to all the wheels (or sets of wheels) and,preferably, with anti-locking devices respectively associated with allwheels (or sets of wheels) each of which is capable of locally modifyingthe braking force which may be applied responsively to accidentalperturbations affecting the corresponding wheel (or set of wheelssubjected to the same command) in continuously measuring, at least forthe entire duration of application of a vehicle braking or slowing downcommand, the angular deceleration of each wheel (or set of wheels) andsumming the same, in constituting the slowing down or braking command inthe form of a reference quantity directly dependent upon a referencedeceleration value of the vehicle, and in slaving the increase ordecrease in the braking power applied to the vehicle to the differencebetween the sum of the angular decelerations on the several wheels (orsets of wheels) and the reference quantity.

In a preferred embodiment of a control and regulating device accordingto the invention for braking or slowing down a vehicle, said deviceincludes measuring instruments associated with each wheel (or set ofwheels) of the vehicle and severally capable of delivering, at least forthe duration of application of a braking command to the vehicle, signalswhich are at all times functions of the actual decelerations of thosewheels (or sets of wheels), and a summing element receiving as inputsall said signals and delivering a working signal which is a function atall times of the sum of said actual decelerations, the said referencequantity being a reference signal whose amplitude is equal to that whichthe working signal would possess if the vehicle were to be subjected toan actual deceleration equal to the reference deceleration, in theabsence of any wheel locking or other unwanted effects, the brakingsystem being slaved in such manner as to then tend to cancel out thedifference between the reference signal and the working signal.

The braking control and regulating device preferably includes inaddition anti-locking elements respectively associated with the wheels(or sets of wheels) of the vehicle, which elements severally utilize thesignals delivered by the measuring instruments respectively associatedwith the same wheels (or sets of wheels), each such anti-locking elementbeing devised so as to suppress, rapidly and momentarily, partly orcompletely, the braking force on the corresponding wheel (or set ofwheels) when the signal issuing from the corresponding measuringinstrument represents a deceleration exceeding a preset threshold.

The invention relates more particularly to certain specific applications(most notably to trains) and to certain specific forms of embodiment,and will be more clearly understood from the description which followswith reference to the accompanying non-limitative exemplary drawing.

The single figure in the drawing represents schematically and in theform of a block diagram a braking control and regulating deviceaccording to this invention, as applied to the wheels of a vehicle.

For a better understanding of the description which follows,consideration will first be given to the case of a single vehiclesupported on two bogies, symbolically designated by la and 10, eachcomprising two axles of which each receives a pair of wheels angularlyrigid with each other, it being understood that all the wheels of thesame bogie will be regarded as belonging to the same set of wheels, allsubjected to the same control forces.

Those parts of the equipment of the vehicle other than the specificmeans which are the object of this invention may be constituted in anyconvenient manner, for instance by providing Westinghouse type brakeunits 2a, 2c, respectively associated to the two bogies and the brakecylinders 3a, 30 of which are supplied with a fluid at variable pressurethrough conduit members 4a, 4c connected to a common conduit 7 suppliedwith a fluid the pressure of which varies according to the requiredbraking power.

The braking command operating on this pressure is preferably obtainedthrough the medium of central control unit 8 comprising an electricallyoperated valve 9 (hereinafter referred to as an electrovalve) actuatedby an electromagnet which is energized by a coil 10.

In its closed position (shown in the figure) which is obtained byenergizing coil 10 with a current of given value I, electrovalve 9interconnects conduit 7 with discharge port 1 1, whereby the brakingforce applied to the train is null. When the current in coil 10decreases, electrovalve 9 causes conduit 7 to be supplied with fluidunder pressure from a pressure-fluid source 12, whereby an increasingbraking force is applied to the wheels of the train. in its openposition, which is obtained with zero current, electrovalve 9 occupies aposition which provides the train with maximum brakmg power.

The pressure of this fluid may be caused to be a direct function of thedrop in current intensity through the coil 10. A direct-controlelectrovalve, i.e., one in which the braking pressure deliveredincreases with increasing current intensity flowing through coil 10,could be substituted for the electrovalve described precedingly. Each ofthe brake units 2a, is furthermore associated to an anti-locking system,likewise well known per se, capable of releasing the braking forceapplied to the associated set of wheels when one of these wheels, or, inthe specific instance herein considered by way of example, when one ofthe axles tends to lock for an unforeseen cause (such as an oil slick onthe rail, or any other accidental impediment liable to cause momentaryloss of adhesion of the wheel in quesion, or a transient maladjustmentof the brake unit itself, etc.

The anti-locking system 37 associated to brake unit 2a may comprise aslide-valve 38 having a two-position pneumatic relay connected intoconduit 4a and controlled by an electrovalve schematically representedat 39. In its first position, slide-valve 38 places brake cylinder 3a incommunication with main supply line 7 and in its second position causesbrake cylinder 3a to be isolated from main supply line 7 and tocommunicate with an expansion chamber 40 having a calibrated externaldischarge orifice 41, whereby the braking force applied to theassociated set of wheels is reduced.

The manner in which electrovalve 39 causes slidevalve 38 to be fetchedrapidly and momentarily into its second position following incipientlocking of one of the axles in the set thereof under consideration willnow be described in greater detail.

It goes without saying that the other brake unit 2c is similarlyassociated to a companion wheel releasing system 49 comprising apneumatic relay type slidevalve 50 connected into conduit element 40 ofbrake unit 2c, and electrovalve 51 capable of moving slidevalve 50 intoa second position upon the onset of phenomena denoting a tendency forone of the axles of bogie 10 to lock, thereby causing brake cylinder 3cto communicate with an expansion chamber 52 having a calibrated orifice53.

Considering next the regulating device portion of the present invention,the same includes measuring instruments 13a and 13b respectivelyassociated to the two axles of the first bogie and delivering signals Sand S which are functions respectively of variations in the angularvelocity of said axles, as well as measuring instruments 13c and 13drespectively associated with the axles of the second bogie anddelivering signals 8;, and S, which are functions respectively of thevariations in the angular velocities of the latter axles, and,

on the one hand, a summing unit 14 fed with the signals 8,, S S and Sand delivering a working signal S which results from the summation ofthese four signals, and a brake-power slaving unit 15 activated by thedifference between working signal S and a reference signal To chosenaccording to the deceleration required for the train, and,

on the other hand, devices 16a, 16c capable of sensing the sudden rapiddeceleration caused by the onset of a phenomenon tending to lock one orthe other of the axles of bogie 1a or one or the other of the axles ofbogie 1c and, when said deceleration exceeds a preset threshold, ofdelivering, at one or the other of their respective outputs 17a and 170,signals capable of energizing one or the other of electro-valves 39, S1of anti-locking systems 36, 49 associated to brake units Although thephenomenon leading to locking of the wheels may already have becomeincipient, for instance in the case of decelerations exceeding -1 meterper second per second in absolute value, it is preferable to set thisthreshold at a relatively high value, for example at -4 meters persecond per second, in order to be able to discriminate between actuallocking phenomena and other causes capable of producing significantvariations in instantaneous decelerations, notably when the wheels runover rail joints, or any other track appliance or break in continuity ofthe track.

Since the measuring instruments 13a, 13b, 13c and 13d are preferablyindentically devised, a description will be given hereinbelow ofmeasuring instrument 13a, it being clearly understood that referencenumerals differing only by their subscripts a, b, c or d designate likeunits. Whereas the measuring instrument 13a may have widely varyingfonns of embodiment, the embodiment illustrated in the accompanyingsingle figure may be resorted to with advantage.

Measuring instrument 13a may include a gearwheel 18a angularly rigid(via a mechanical link symbolized by the dot-dash line 6) with the axleto which instrument 13a is associated, said gearwheel having teeth (notshown) made of magnetic material,

a sensor 19a which comprises an air gap through which the teeth ofgearwheel 18a move as the latter rotates and which delivers analternating voltage of frequency proportional to the angular velocity ofthe rotating axle,

a shaping unit 20a which transforms the alternating voltage issuing fromthe sensor into a series of square pulses,

a frequency multiplier 21a which delivers a series of pulses thefrequency of which is, say, double that of the train of pulses issuingfrom unit 20a and applied to multiplier 21a, whereby the resolving powerof the measuring instrument is increased, notably when, because thetrain is travelling at low speed, the frequency of the al- Iematingvoltage produced by sensor 19a is relatively a converter 22a capable ofconverting the train of pulses issuing from multiplier 21a, notably intoa direct voltage which is at all times proportional to the frequency ofsaid train of pulses and a differentiating unit 230 capable ofgenerating a signal S which is the derivative of the DC. voltage issuingfrom converter 22a. It should be noted that the voltage S is at alltimes proportional to the rate of change of angular velocity of the axleto which measuring instrument 13a is associated and that the sameapplies in the case of voltages S S and S respectively.

In a preferred form of embodiment of the invention, summing unit 14 isformed by an operational amplifier 24 connected in an adderconfiguration and receiving as inputs, through the medium of impedancematchers 30a, 30b, 30c, 30d, the signals 8,, S S and S The slaving unitis formed by an operational amplifier 25 connected in a subtractorconfiguration and receiving, through one input 26, a signal S obtainedthrough the medium of a potentiometer 28 which divides the value of theoutput signal from amplifier 24 by the number of signals 8,, S S S (i.e.by four in this instance), and, through another input 27, the signal Icrepresenting the rate of deceleration chosen for the train.

This signal P c, which is the braking control signal, can assumedifferent values to correspond to the required braking conditions and,in particular, may emanate from a manual control 29 for governing thespeed of the train, having a plurality of notches F F F and which,depending on the notch selected, is capable of applying to the input 27on operational amplifier 25, one of several predetermined referencedeceleration values Fc.

Obviously, this reference deceleration may issue from any otherconvenient source. In the case for example of an automatically drivenvehicle, this reference deceleration could be applied to it from apreset program set up along the track followed by the vehicle, forinstance (as well know per se) through the medium of a driver cablewhich is the seat of an electric current and is disposed along the trackin such manner as to induce aboard the vehicle, at successive placesalong the track, signals which are automatically processed by thepiloting system so as to correct the true decelerations of the vehicle,notably at places along its path at which it is required to slow down.

The output voltage from operational amplifier 25, which is at all timesdirectly proportional to the difference between the referencedeceleration Fe and the working signal S is then applied to the input ofthe winding 10 of master braking control unit 8 through the medium of apower amplifier (not shown) delivering an output current capable ofmodulating the input current to winding 10, in order to command areduction or increase in braking power that is at all timesproportionate to the regulating action triggered by the measuring andsumming devices, whereby to cause the difference between the voltages Feand S to tend to cancel out. It goes without saying that the subjectcontrol and regulating device of this invention must be capable ofreferencing the braking function to the deceleration of the train onlywhen a braking command is actually applied to the device, and notablywhen one of the notches F to F of control 29 is selected. In particular,there must be no intervention by the said control device when the trainis decelerated while under traction, for instance as it begins to ascenda gradient, and this can be accomplished by clamping the operationalamplifier 25 when none of said notches is selected.

It is to be noted in particular that it is possible with a control andregulating device of this kind to impose a constant speed, notably whenrunning downhill, provided that one of the predetermined referencevalues Ic capable of being applied to the input 27 of operationalamplifier 25 is equal to zero.

Preferably, the sensing device 16a associated to the wheel braking unit2a of the first bogie 1a comprises two threshold type elements 31 and32, capable of switching from a first stable state to a second stablestate when the signals S and S which they respectively receive viaimpedance matchers 33, 34 respectively exceed a given thresholdcorresponding, say, to an actual deceleration equal in absolute value to4 meters per second per second, and capable subsequently of switchingfrom the second to the first stable state when the signals S and Sassume positive values corresponding to an acceleration of the wheelsequal, for instance, to +3 meters per second per second, said thresholdtype elements being adapted, when in their second state, to energize theelectrovalve 39 of anti'locking system 37 through power amplifiers 35,36 whereby to rapidly, temporarily and at least partly remove the axlesof bogie la from the action of braking unit 2a.

The sensing device 16c is similarly devised to the device 16a describedhereinabove and includes two impedance matchers 45 and 46 feeding thesignals S S to two threshold type elements 43 and 44 which, via poweramplifiers 47 and 48, are capable of energizing the electrovalve 51 ofanti-locking system 49 when the true deceleration measured on one of theaxles of bogie 1c exceeds 4 meters per second per second. Manifestly, inthe general case where there is no tendency for any of the vehicle axlesto lock, the antilocking systems will not be activated, so that the sumof the signals 8,, S S S can then be regarded as being representative ofthe actual deceleration of the vehicle, with the signal obtained uponapplication of a braking command to the input 27 of operationalamplifier 25 then representing the difference between the actualdeceleration of the vehicle and the reference deceleration value. Insuch cases the control and regulating device of this invention willbehave like the prior art devices referred to precedingly, making it isunnecessary to describe the manner of its operation in any detail.

In the event, however, of the onset of phenomena likely to cause lockingof the axle of the bogie 1a associated with gearwheel 18a, the resultingsudden increase in deceleration will cause differentiating unit 23a todeliver a signal S, of likewise suddenly increasing magnitude, which,when it exceeds the threshold corresponding to a deceleration of 4meters per second per second, causes threshold unit 31 to switch intoits second state and thereby energizes electrovalve 39 of anti-lockingsystem 37 and in turn causes the braking unit 2a operating on the wheelsof bogie 1a to lrelease its effect for as long as the tendency to lockasts.

If, initially, the said increase in magnitude of signal 8, should tendto reduce or even nullify the modulated control signal output fromoperational amplifier 25, the interruption in this tendency to lock,following activation of anti-locking system 37 (which interruption thencauses threshold element 35 to revert to its first state), will tend onthe contrary to enhance the braking pres sure in the supply conduit 7 ofthe common braking circuit, due to the change in the sign of signal S(resulting from the acceleration to which the released wheel is thensubjected) and the attendant decrease in magnitude of working signal SThe brake unit 20, which is not affected by the anti-locking effect, isthen capable of acting as a back-up unit upon temporary failure of brakeunit 20, and to do so for as long as the tendency of the axle underconsideration to lock is not definitively overcome.

Whereas the foregoing description has been confined for exemplarypurposes to the case of a vehicle equipped with two bogies, each ofwhich is associated to a single brake unit and a single anti-lockingsystem, it goes without saying that it would be possible to utilize anindependent anti-locking system for each axle of the same bogie (or evenfor each of the wheels if the latter are independent) that would becapable of rapidly, mo-

'mentarily, and at least partly withdrawing, from the braking forceapplied to all the wheels of the bogie,

only the specific axle under consideration (when it tends to lock).

Similarly, consideration has been given hereinbefore only to the case ofan independent vehicle. Clearly, however, in the case of a train eachcoach of which is equipped with a braking force regulating system whichis independent but nonetheless slaved to a control signal common to allthe coaches of the train,

it is possible to obtain even more precise regulation entirelyindependent of successively occurring local phenomena which denote atendency of the axles on each coach to lock,.owing for example to thepresence of an oil slick on the rails at some specific place along thetrack, but which are in any case immediately compensated for.

It goes without saying that many changes and substitutions of parts maybe made without departing from the scope of the invention and that, inits broader aspects, the invention is by'no means limited to thespecific examples of application hereinbefore described for purelyexamplary purposes.

For instance, the anti-locking system described precedingly could bereplaced by any other known type of anti-locking or releasing systemsuch as a system of the kind based on a comparison between the speeds oftwo or more neighboring wheels.

Further, it would alternatively be possible to regulate the accelerationof a vehicle, the brake units being then replaced by traction units andthe anti-locking systems by devices which, in the event of wheel slip,are designed either to reduce the traction force or to improve wheeladhesion on the track (by sanding for example).

In particular, the device for controlling and regulating the runningconditions of a vehicle, described hereinabove with reference to brakingor slowing down of the vehicle, could additionally include a summingunit so devised as to be capable also of referencing an increase ordecrease in traction power to the difference between the accelerationsmeasured (e.g. by said measuring instruments) and a traction commanddependent upon a preset reference acceleration value, and units whichwould each process the signal furnished by said measuring instrumentswhereby to rapidly, momentarily and at least partly suppress thetraction force applied to the associated wheels whenever the signaldelivered by the measuring instrument associated with one of the wheels(or sets of wheels) of the vehicle represents an acceleration (tendencyto slip) of said wheel (or said set of wheels) in excess of a presetthreshold.

What is claimed is:

1. In a control system for a vehicle having a plurality of wheels andmeans for applying force thereto to change the speed of rotationthereof, the improvement comprising means responsive to the rotationalspeeds of the respective traction wheels and adapted to provide outputsproportional to rate of change therein, means for relieving the forceapplied to any wheel when the output so provided therefrom exceeds acertain value, means for summing the outputs so provided and forcomparing the sum thereof with a predetermined value, and meansresponsive to the result of such comparison and adapted to alter theapplied force so as to equalize the output sum to the predeterminedvalue.

2. Control system according to claim 1, wherein the last means comprisesa plurality of speed-altering means, each operatively connected to aseparate plurality of independently rotatable traction wheels,individually provided with aforesaid speed-sensing means andforce-relieving means.

3. A system for controlling and regulating the braking of a vehiclewhich comprises a braking circuit common to a plurality of wheels (orsets of wheels) of the vehicle,

measuring means associated with each of said wheels (or sets of wheels)severally adapted to deliver, at least for the entire duration ofapplication of a braking effort on said wheels, individual electricalsignals the values of which are respectively proportional at all timesto the actual decelerations of the associated wheels (or sets ofwheels),

anti-locking means respectively associated with said wheels (or sets ofwheels) each of which is individually responsive to the correspondingindividual electrical signal for at least partly, rapidly andmomentarily, eliminating the braking force exerted on the correspondingwheel (or set of wheels) when said individual signal exceeds apredetermined threshold,

a summing unit for summing all of said individual electric signals anddelivering a working signal dependent at all times upon the sum of saidindividual electric signals,

referencing means for producing a braking or slowing down signal,representative of a preset reference deceleration for the vehicle, and

control means for slaving the braking power applied to all wheels (orsets of wheels) through said braking circuit to the difierence betweensaid braking or slowing down command signal and said working signal.

4. A system according to claim 3, wherein the value of said braking orslowing down command signal is equal to the value which the workingsignal would have if the vehicle were subjected to an actualdeceleration equal to the said preset reference deceleration, in theabsence of any wheel-locking tendency or other disrupting factor.

5. A system according to claim 4, wherein said control means are adaptedto slave the braking power applied to said wheels through said commoncircuit such as to cause the difference between the braking or slowingdown command signal and the working signal to be cancelled out.

6. A system according to claim 5, wherein the summing element comprisesa first operational amplifier connected in a summing configuration andreceiving upon its various inputs the signals supplied by all of saidmeasuring means and said control means include a second operationalamplifier connected in a subtractor configuration and receiving througha first input the working signal issuing from the first operationalamplifier and through another input the braking or slowing down commandsignal.

7. A system according to claim 3, wherein said antilocking meansrespectively comprise threshold type elements each adapted to switchfrom a first to a second stable state when the individual signal sodelivered and applied to its input exceeds said threshold, whereuponsaid anti-locking means is actuated to effect said rapid and momentaryelimination of the braking force on the wheels (or sets of wheels)associated therewith.

8. A system according to claim 7, wherein said threshold type elementsare additionally adapted to switch from the second to the first stablestate when the individual signals applied to their respective inputsassume a positive value corresponding to a certain acceleration of thewheels, whereupon said anti-locking means returns to its formercondition and said momentarily eliminated braking force is reasserted.

9. A system for controlling and regulating the braking of a vehiclewhich comprises brake means operable by a fluid under pressure andassociated with each of a plurality of wheels (or sets of wheels) of thevehicle,

a conduit common to said brake means for supplying said fluid theretoand electrovalve means controlled by a control signal to regulate thepressure of said fluid in said conduit,

measuring means associated with each of said wheels (or sets of wheels)severally adapted to deliver, at least for the entire duration ofapplication of a braking effort on said wheels, individual electricalsignals the values of which are respectively proportional at all timesto the actual decelerations of the associated wheels (or sets ofwheels),

anti-locking means respectively associated with each of said wheels (orsets of wheels) each of which comprises a threshold type elementsupplied on its input with the individual electric signal delivered bythe corresponding measuring means and adapted to switch from a first toa second stable iifiiililifvifilfig fi ai d lfiiii ina ll i adapted toeffect a rapid and momentary elimination of the braking force applied onthe wheel (or set of wheels) associated therewith, and to switch backfrom the second to the first stable state, when said individual signalassumes a positive value corresponding to a certain acceleration of thecorresponding wheel (or set of wheels), whereupon said anti-lockingmeans returns to its former condition and said momentarily eliminatedbraking force is reasserted,

a first operational amplifier connected in a summing configuration andreceiving upon its various inputs the individual signals supplied by allof said measuring means and delivering a working signal dependent at alltimes upon the sum of said individual signals,

referencing means for producing a braking or slowing down signalrepresentative of a preset reference deceleration for the vehicle,

a second operational amplifier connected in a subtractor configurationand receiving on a first input said working signal and on another inputsaid braking or slowing down command signal and delivering an outputsignal dependent at all times upon the difference of said working signaland said braking or slowing down command signal,

said output signal constituting said control signal.

10. A system for controlling and regulating the traction of a vehiclewhich comprises a traction circuit common to a plurality of wheels (orsets of wheels) of the vehicle,

measuring means associated with each of said wheels (or sets of wheels)severally adapted to deliver, at least for the entire duration ofapplication of a traction effort on said wheels, individual electricsignals the values of which are respectively proportional at all timesto the actual decelerations of the associated wheels (or sets of wheels)anti-slipping means respectively associated with each of said wheels (orsets of wheels), individually responsive to the corresponding individualelectric signal for at least partly, rapidly and momentarily,eliminating the traction force exerted on the corresponding wheels (orsets of wheels) when said electrical individual signal exceeds apredetermined threshold,

a summing unit for summing all of said individual electrical signals anddelivering a working signal dependent at all times upon the sum of saidindividual electric signals,

referencing means for producing a traction signal representative of apreset reference acceleration for the vehicle, and

control means for slaving the traction power applied to all wheels (orsets of wheels) through said circuit to the difference between thetraction signal and said working signal.

1. In a control system for a vehicle having a plurality of wheels andmeans for applying force thereto to change the speed of rotationthereof, the improvement comprising means responsive to the rotationalspeeds of the respective traction wheels and adapted to provide outputsproportional to rate of change therein, means for relieving the forceapplied to any wheel when the output so provided therefrom exceeds acertain value, means for summing the outputs so provided and forcomparing the sum thereof with a predetermined value, and meansresponsive to the result of such comparison and adapted to alter theapplied force so as to equalize the output sum to the predeterminedvalue.
 2. Control system according to claim 1, wherein the last meanscomprises a plurality of speed-altering means, each operativelyconnected to a separate plurality of independently rotatable tractionwheels, individually provided with aforesaid speed-sensing means andforce-relieving means.
 3. A system for coNtrolling and regulating thebraking of a vehicle which comprises a braking circuit common to aplurality of wheels (or sets of wheels) of the vehicle, measuring meansassociated with each of said wheels (or sets of wheels) severallyadapted to deliver, at least for the entire duration of application of abraking effort on said wheels, individual electrical signals the valuesof which are respectively proportional at all times to the actualdecelerations of the associated wheels (or sets of wheels), anti-lockingmeans respectively associated with said wheels (or sets of wheels) eachof which is individually responsive to the corresponding individualelectrical signal for at least partly, rapidly and momentarily,eliminating the braking force exerted on the corresponding wheel (or setof wheels) when said individual signal exceeds a predeterminedthreshold, a summing unit for summing all of said individual electricsignals and delivering a working signal dependent at all times upon thesum of said individual electric signals, referencing means for producinga braking or slowing down signal, representative of a preset referencedeceleration for the vehicle, and control means for slaving the brakingpower applied to all wheels (or sets of wheels) through said brakingcircuit to the difference between said braking or slowing down commandsignal and said working signal.
 4. A system according to claim 3,wherein the value of said braking or slowing down command signal isequal to the value which the working signal would have if the vehiclewere subjected to an actual deceleration equal to the said presetreference deceleration, in the absence of any wheel-locking tendency orother disrupting factor.
 5. A system according to claim 4, wherein saidcontrol means are adapted to slave the braking power applied to saidwheels through said common circuit such as to cause the differencebetween the braking or slowing down command signal and the workingsignal to be cancelled out.
 6. A system according to claim 5, whereinthe summing element comprises a first operational amplifier connected ina summing configuration and receiving upon its various inputs thesignals supplied by all of said measuring means and said control meansinclude a second operational amplifier connected in a subtractorconfiguration and receiving through a first input the working signalissuing from the first operational amplifier and through another inputthe braking or slowing down command signal.
 7. A system according toclaim 3, wherein said anti-locking means respectively comprise thresholdtype elements each adapted to switch from a first to a second stablestate when the individual signal so delivered and applied to its inputexceeds said threshold, whereupon said anti-locking means is actuated toeffect said rapid and momentary elimination of the braking force on thewheels (or sets of wheels) associated therewith.
 8. A system accordingto claim 7, wherein said threshold type elements are additionallyadapted to switch from the second to the first stable state when theindividual signals applied to their respective inputs assume a positivevalue corresponding to a certain acceleration of the wheels, whereuponsaid anti-locking means returns to its former condition and saidmomentarily eliminated braking force is reasserted.
 9. A system forcontrolling and regulating the braking of a vehicle which comprisesbrake means operable by a fluid under pressure and associated with eachof a plurality of wheels (or sets of wheels) of the vehicle, a conduitcommon to said brake means for supplying said fluid thereto andelectrovalve means controlled by a control signal to regulate thepressure of said fluid in said conduit, measuring means associated witheach of said wheels (or sets of wheels) severally adapted to deliver, atleast for the entire duration of application of a braking effort on saidwheels, individual electrical signals tHe values of which arerespectively proportional at all times to the actual decelerations ofthe associated wheels (or sets of wheels), anti-locking meansrespectively associated with each of said wheels (or sets of wheels)each of which comprises a threshold type element supplied on its inputwith the individual electric signal delivered by the correspondingmeasuring means and adapted to switch from a first to a second stablestate when said individual signal exceeds a given threshold, whereuponsaid anti-locking means is adapted to effect a rapid and momentaryelimination of the braking force applied on the wheel (or set of wheels)associated therewith, and to switch back from the second to the firststable state, when said individual signal assumes a positive valuecorresponding to a certain acceleration of the corresponding wheel (orset of wheels), whereupon said anti-locking means returns to its formercondition and said momentarily eliminated braking force is reasserted, afirst operational amplifier connected in a summing configuration andreceiving upon its various inputs the individual signals supplied by allof said measuring means and delivering a working signal dependent at alltimes upon the sum of said individual signals, referencing means forproducing a braking or slowing down signal representative of a presetreference deceleration for the vehicle, a second operational amplifierconnected in a subtractor configuration and receiving on a first inputsaid working signal and on another input said braking or slowing downcommand signal and delivering an output signal dependent at all timesupon the difference of said working signal and said braking or slowingdown command signal, said output signal constituting said controlsignal.
 10. A system for controlling and regulating the traction of avehicle which comprises a traction circuit common to a plurality ofwheels (or sets of wheels) of the vehicle, measuring means associatedwith each of said wheels (or sets of wheels) severally adapted todeliver, at least for the entire duration of application of a tractioneffort on said wheels, individual electric signals the values of whichare respectively proportional at all times to the actual decelerationsof the associated wheels (or sets of wheels) anti-slipping meansrespectively associated with each of said wheels (or sets of wheels),individually responsive to the corresponding individual electric signalfor at least partly, rapidly and momentarily, eliminating the tractionforce exerted on the corresponding wheels (or sets of wheels) when saidelectrical individual signal exceeds a predetermined threshold, asumming unit for summing all of said individual electrical signals anddelivering a working signal dependent at all times upon the sum of saidindividual electric signals, referencing means for producing a tractionsignal representative of a preset reference acceleration for thevehicle, and control means for slaving the traction power applied to allwheels (or sets of wheels) through said circuit to the differencebetween the traction signal and said working signal.